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1.
Geologic relations indicate that silica phases transformed in the Monterey Formation in two zones that persist over a narrow
depth/temperature range and do not stratigraphically overlap. The wide and overlapping range of reported temperatures of these
transformations is mainly a result of the many uncertainties inherent in the different methods used to estimate temperature
and does not indicate that phases transform throughout these ranges. Our approach to a reliable temperature scale for silica
diagenesis combines as empirical zonation of silica phases with temperature calibration from a sequence at maximum temperature
and depth of burial. 相似文献
2.
Shanshan Zhou Youchuan Li Jianping Li Wenjing Ding Xin Li Weilai Zhang 《海洋学报(英文版)》2023,42(3):138-150
The terrigenously-dominated marine shales which were deposited in the lower Eocene Pinghu Formation were thought to be a potential source rock in the Xihu Depression of the East China Sea Shelf Basin. However, the exceptionally high total organic carbon content (TOC, >6% on average) of the tidal sand ridge samples was not compatible with their sedimentary environment, indicating coal-bearing sedimentary debris may have been transferred from the coast to the ocean. In this study, new sights into the origins and supply of organic materials in the coastal environment were proposed in the neritic organic matter of the Eocene Pinghu Formation. A discriminant model was developed using plynofacies analysis data to pinpoint the source of organic materials in marine source rocks. The discrimination results suggested that marine mudstones were associated with tidal flat mudstones rather than deltaic ones. The biomarker characteristics of mudstones deposited in various environments support this assertion, indicating that the supply of plant materials in tidal flats is the primary organic matter source for the marine environment. The organic matter abundance was elevated in tidal flats due to their superior preservation conditions. Additionally, the lithological assemblage of tidal flats suggests that tidal currents can scour marshes and then transport dispersed terrigenous organic materials to neritic areas. These findings indicate that coal-bearing sedimentary debris was likely transferred from the coast to the ocean, and tidal currents are thought to be the dominant mechanism driving organic matter from the tidal to the marine environment. 相似文献
3.
James P. Barry H. Gary Greene Daniel L. Orange Charles H. Baxter Bruce H. Robison Randall E. Kochevar James W. Nybakken Donald L. R Cecilia M. McHugh 《Deep Sea Research Part I: Oceanographic Research Papers》1996,43(11-12)
Cold seep communities discovered at three previously unknown sites between 600 and 1000 m in Monterey Bay, California, are dominated by chemoautotrophic bacteria (Beggiatoa sp.) and vesicomyid clams (5 sp.). Other seep-associated fauna included galatheid crabs (Munidopsis sp.), vestimentiferan worms (Lamellibrachia barhami?), solemyid clams (Solemya sp.), columbellid snails (Mitrella permodesta, Amphissa sp.), and pyropeltid limpets (Pyropelta sp.). More than 50 species of regional (i.e. non-seep) benthic fauna were also observed at seeps. Ratios of stable carbon isotopes (δ13C) in clam tissues near 36‰ indicate sulfur-oxidizing chemosynthetic production, rather than non-seep food sources, as their principal trophic pathway. The “Mt Crushmore” cold seep site is located in a vertically faulted and fractured region of the Pliocene Purisima Formation along the walls of Monterey Canyon ( 635 m), where seepage appears to derive from sulfide-rich fluids within the Purisima Formation. The “Clam Field” cold seep site, also in Monterey Canyon ( 900 m) is located near outcrops in the hydrocarbon-bearing Monterey Formation. Chemosynthetic communities were also found at an accretionary-like prism on the continental slope near 1000 m depth (Clam Flat site). Fluid flow at the “Clam Flat” site is thought to represent dewatering of accretionary sediments by tectonic compression, or hydrocarbon formation at depth, or both. Sulfide levels in pore waters were low at Mt Crushmore (ca 0.2 mM), and high at the two deeper sites (ca 7.011.0 mM). Methane was not detected at the Mt Crushmore site, but ranged from 0.06 to 2.0 mM at the other sites. 相似文献
4.
Hartwell SI 《Marine environmental research》2008,65(3):199-217
Sediment samples were collected to delineate the distribution of contaminants along the central California coast. Sampling included a variety of Canyons and shelf/slope areas to evaluate contaminant transport patterns and potential delivery to Canyons and the continental slope to a depth of 1200 m. Sediments were collected and analyzed for organic contaminants using standard techniques of the NOAA National Status and Trends Program (NS&T). DDT is distributed on the shelf within a zone of fine-grained sediments between Half Moon and Monterey Bays. DDT was found at higher concentrations in Ascension, A?o Nuevo, and Monterey/Soquel Canyons than in Pioneer and Carmel Canyons, the Gulf of the Farallones, or the continental slope. The Monterey Bay watershed appears to be the primary source of DDT. In contrast, PAHs and PCBs on the shelf appear to be derived primarily from San Francisco Bay. DDT appears to be delivered to the deep ocean via the Canyons more than from cross-shelf sediment transport. Sediment budget estimates for the continental shelf north of Monterey Bay need further refinement and more data to account for the movement of material from Monterey Bay onto the shelf. 相似文献
5.
在烃源岩分布特征、有机质丰度、类型和成熟度分析的基础上,运用含油气盆地数值模拟技术,定量恢复了烃源岩热成熟演化史,探讨了油气差异分布特征。研究表明,文昌A凹陷各层系烃源岩分布广,厚度大,有机质丰度高;有机质类型文昌组偏Ⅱ1型,恩平组偏Ⅲ型,二者现今多处于高成熟—过成熟阶段。凹陷内烃源岩成熟时间早(文昌组约45.5Ma),现今成熟度高,以干气生成为主;凹陷边缘烃源岩成熟时间较晚(文昌组约30.0Ma),现今成熟度相对较低,以石油生成为主。凹陷现今油气差异分布的格局受制于有机质类型差异和热演化史不同,且下一步油气勘探方向,凹陷内以天然气为主,凹陷边缘以石油为主。 相似文献
6.
东海西湖凹陷浙东中央背斜带烃源岩生排烃史研究 总被引：9，自引：1，他引：9
为了深化西湖凹陷浙东中央背斜带油气成藏过程的研究，优化勘探目标选择，在烃源岩特征分析的基础上，应用动态数值模拟技术，定量恢复了研究区主要烃源岩层系的生排烃历史，研究表明，浙东中央背斜带主要发育4套烃源岩系，其中始新统平湖组泥岩与煤层为主力烃源岩，具较高的有机质丰度=生烃强度与排烃效率，烃类排出具阶段性、多期次幕式排烃的特点汉平湖组为源岩的油气系统应是本区油气勘探的主要目标。 相似文献
7.
Dilution by inert, refractory organic carbon can have a significant impact on the hydrocarbon potential of source rocks. In this study, a correction of total organic carbon, based on petrographic observations, is proposed to give a better indication of hydrocarbon generation potential. This correction shows that although the Second White Specks Formation is an excellent hydrocarbon source rock, hydrogen index and total organic carbon are influenced by dilution from refractory organic carbon of various sources. The results show that a higher degree of dilution occurs within the Belle Fourche Formation than the Second White Specks Formation. This dilution can have a significant impact on the hydrocarbon potential of the rock.Volumetric calculation of the inert carbon fraction using organic petrographic methods provides a semi quantitative method to correct total organic carbon values for the refractory organic carbon dilution effect. Incorporation of the dilution corrected organic carbon value in hydrogen index calculations allows a greater understanding of source rock hydrocarbon potential. This method provides better differentiation of the small scale variation between micro-facies and formation, as observed in the Second White Specks and Belle Fourche formations, than traditional bulk geochemical methodologies and previously proposed correction methodologies. Degree of dilution, either through transport of recycled allochthonous or autochthonous reworking of organic matter in-situ is highly variable and represents a significant challenge in the characterization of heterogeneous source rocks.This study investigates the organic petrology and geochemistry of a sediment core from the thermally immature area of the Upper Cretaceous Second White Specks Formation and Belle Fourche Formation. Reflectance and relative abundance of three maceral groups (bituminite, alginite, and refractory organic carbon macerals) showed significant organic matter compositional differences between micro-facies in the Second White Specks Formation. A change is also observed in organic matter composition from the upper part of the Belle Fourche Formation to the Second White Specks Formation. These compositional changes represent shifts in sediment source, sea floor oxygen levels, and depositional energy levels. These changes can be episodic, as observed between micro-facies, or longer time scale trends, as observed between the studied formations. 相似文献
8.
赣东–浙西下寒武统荷塘组稀土元素特征及其地质意义 总被引：1，自引：0，他引：1
为揭示下扬子下寒武统黑色岩系的物源属性、构造背景及其沉积环境等特征,对赣东-浙西地区下寒武统荷塘组野外露头及钻井岩心进行了系统采样与稀土元素分析测试。结果显示,荷塘组样品稀土元素总量变化波动大(16.83×10-6~321.22×10-6),均值低(103.11×10-6),轻稀土元素富集且分异明显,重稀土元素亏损但分异小,普遍存在Ce负异常和明显Eu正异常。研究表明:①荷塘组硅质泥页岩形成于缺氧还原的裂陷海盆环境,构造背景为被动大陆边缘,物源受陆源、海水和热液共同影响,横峰、上饶受热液和海水影响最大,受陆源碎屑影响最小,常山、江山与之相反;②沉积过程普遍有热液活动参与,在上饶存在热液活动中心,活动强度呈西强东弱特点,并发现低温热液活动有利于有机质的富集。 相似文献
9.
Norbert Dankers Michel Binsbergen Koos Zegers Remi Laane Michiel Rutgers van der Loeff 《Estuarine, Coastal and Shelf Science》1984,19(2):143-165
Transport processes were studied in a gully between a salt marsh and an estuary. After storm tides, ebb currents in the gully reached high values. It is concluded that particulate matter (both organic and inorganic) are imported into the marsh. Coarse organic debris is exported during storm tides, but this amount is low when compared with the primary production on the marsh. Exports are shown for dissolved organic carbon, ammonia, phosphate and silica, while nitrate and possibly nitrite are imported. Organic matter derived from in situ production and net import is buried and partly mineralized in the marsh. 相似文献
10.
There are three major fan valleys on upper Monterey fan. Deep-tow geophysical profiles and 40 sediment cores provide the basis for evaluation of the sedimentation histories of these valleys. Monterey fan valley leads from Monterey canyon to a major suprafan and is bounded by levees that crest more than 400 m above the valley floor. The valley passes through a large z-bend or meander. Monterey East fan valley joins Monterey fan valley at the meander at about 150 m above the valley floor, and marks an earlier position of the lower Monterey fan valley. Ascension valley, a hanging contributary to the Monterey fan valley, appears to have once been the shoreward head of the lower part of the present Monterey fan valley. The relief of Monterey fan valley appears from deep-tow profiles to be erosional. The valley is floored with sand. Holocene turbidity currents do not overtop the levees 400 m above the valley floor, but do at times overflow and transport sand into Monterey East valley, producing a sandy floor. An 1100 m by 300 m dune field was observed on side scan sonar in Monterey East valley.Ascension fan valley was floored with sand during glacial intervals of lowered sea level, then was cut off from its sand source as sea level rose. A narrow (500 m), erosional, meandering channel was incised into the flat valley floor; the relief features otherwise appear depositional, with a hummocky topography perhaps produced in the manner of a braided riverbed. The sand is mantled by about 6 m of probable Holocene mud. Hummocky relief on the back side of the northwestern levees of both Ascension and Monterey valleys is characteristic of many turbidite valleys in the northeast Pacific. The hummocky topography is produced by dune-like features that migrate toward levee crests during growth. 相似文献
11.
西湖凹陷中-下始新统宝石组油气地质与勘探潜力 总被引：13，自引：0，他引：13
西湖凹陷是东海陆架盆地油气勘探潜力最好的凹陷之一。通过西湖凹陷宝石一井中下始新统宝石组井震资料,厘定了影响油气资源计算结果较大的关键参数,如烃源岩厚度、有机质油气产率、排聚系数等;建立了构造、沉积、孔隙度与油气生、运、聚模型,编绘了西湖凹陷宝石组生油岩厚度图、有机碳、Ro、生油气强度等值线图;采用BASIMS 4．5盆地综合模拟系统重现了西湖凹陷宝石组的地史、热史、生烃史、排烃史和运聚史,分析了宝石组空间展布特征与生、储、盖、圈、运、保等地质条件,提出并建立了宝石组合油气系统。利用多种方法定量计算的宝石组生烃量和资源量与西湖凹陷已证实的主力烃源岩系平湖组相似,认为宝石组是西湖凹陷又一重要烃源岩及油气勘探目的层系,拥有巨大的油气勘探潜力。 相似文献
12.
南大洋普里兹湾沉积物中生物硅含量与分布 总被引：1，自引：2，他引：1
利用中国第18,21次南极考察获得的沉积物样品,对南大洋普里兹湾沉积物中生物硅(BSiO2)的含量以及分布特征进行了初步研究.结果表明:普里兹湾表层沉积物中生物硅含量丰富,生物硅含量在4.89%~85.41%之间变化,平均为30.90%.最高值出现在湾内的IV-10站.生物硅的垂向分布与间隙水中硅酸盐呈现相反的变化趋势.表层沉积物中生物硅和有机碳分布趋势与表层海水中叶绿素a、初级生产力的分布趋势密切相关,最大值均出现在普里兹湾环流中心区域,较好地反映了上层水体中初级生产力的变化状况. 相似文献
13.
Marine carbonate rocks are widespread and their sedimentary layers are huge and thick.Many oil seepages outcrops are found in the Middle-Upper Proterozoic of North China. Combined with previous data, the paper discusses the evaluation criteria of marine carbonate source rocks.Many factors,such as organic matter types of source rocks,thermal maturity,mineral and chemical composition,paleotemperature and source-reservioir relationship etc. Should be considered. Therefore,the abundance cutoff criteria of organic matters in North China especially in the Southern area,needs further.In this paper,North China is divided into the north area dn the south area,and the organic matter type,organic matter abundance and degree of thermal evolution of organic matter in the two areas in overall and both of them are high thermal evaluation level.Furthermore,the majority of the organic matters of the source rock have been in highly over matured phase.Source rock mature period of Liulaobei Formation and Xuhuai Group in the southern area ids equal to that of the lower Xiamalin Formation in the northern area,the hydrocarbon generation capacity of Chuanlinggou Formation,and different organic matter types obtained with different methods on source rock research in the south area of North China are also put forward. 相似文献
14.
Semidiurnal internal tides in Monterey Canyon are shown to be partially responsible for macronutrient enrichment of surface waters in Monterey Bay, California. CTD time series at five stations in the canyon revealed the presence of semidiurnal internal tides with heights between 50 and 120 m. p Thermistor data demonstrated an internal tidal bore at the head of the canyon. Data and theory suggest that internal tidal bores may be breaking, due to either shear instability or direct overturning, thereby enriching the immediate area near the canyon head.Transects normal to Monterey Canyon showed a 20-m thick lens of 12 °C water moving out of the canyon at high internal tide. This lens was then pinched off from the canyon, and led to a density-induced divergence. The nutrient transport associated with the internal tidal divergence could support as much as 30% of the daily primary productivity in the northern part of Monterey Bay during non-upwelling periods. 相似文献
15.
Roberta K. Smith-Evernden 《Geo-Marine Letters》1985,5(1):37-38
All 146,039 foraminifera obtained from twenty-four 5-ml replicate samples taken 10-cm apart along one 8-cm thick bed in the
Monterey Formation were identified and counted. Replicates 1 through 19 and 20 through 24 differ taxonomically and, very significantly,
numerically. Differences probably reflect postmortem transport, small-scale ecological variations, and possibly other phenomena.
Such foraminiferal distributions can assist both the determination of sampling adequacy and sedimentation processes themselves. 相似文献
16.
上新世——早更新世青藏高原北缘隆升的磁性地层学证据 总被引：9，自引：0，他引：9
对新疆叶城剖面西域砾岩及下伏第三纪地层的磁性地层学研究表明 ,西域砾岩的沉积时代为晚上新世至早更新世 ,磁性地层年龄为 3.5至 <1.8Ma。阿图什组沉积于早上新世 ,古地磁年龄为 4 .6～ 3.5 Ma。阿图什组以砂岩和粉砂岩为主夹薄层砾岩 ,为河流相及冲积扇前缘相。西域砾岩以厚层砾岩为主夹风成粉砂岩 ,为典型洪积—冲积扇堆积。西域砾岩的沉积反映了青藏高原北缘晚上新世至早更新世强烈的隆起和剥蚀 相似文献
17.
琼东南盆地深水区L18气田上新统地层圈闭气田形成条件及成藏模式 总被引：2，自引：1，他引：1
近期在琼东南盆地超深水区发现了L18气田上新统地层圈闭气田，但在聚气背景、烃源岩、储层沉积成因及天然气输导体系等气田形成条件和成藏模式认识存在争议。通过对该气田形成条件的综合分析，认为上新世轴向古洼槽内地层圈闭、陵水凹陷东洼下渐新统崖城组浅海相烃源岩、上新统限制型重力流砂岩储层和渐新统-中新统断裂垂向沟源通道是形成上新统地层圈闭气田的4个基本条件。中中新世以来盆地中央继承性发育轴向古洼槽和限制型重力流沉积，随着后期地层沉积迁移、差异压实作用，上新统莺歌海组砂岩顶面在轴向洼槽内起伏，并被周边泥岩封盖、封堵，形成了地层圈闭；约3.4 Ma BP，陵水凹陷东洼下渐新统崖城组浅海相烃源岩生成了成熟天然气，沿渐新统-中新统断裂向上运移到上新统莺歌海组重力流沉积砂岩中，再侧向运移至地层圈闭中聚集成藏，具有"烃源岩、圈闭、断裂+砂岩输导层"三要素控藏的上新统地层圈闭成藏模式。 相似文献
18.
The Late Cretaceous sedimentary record of the North American Western Interior Seaway is characterized by cyclic deposition of organic carbon-rich sediments. One notable interval during the late Coniacian-Santonian is recorded by the Niobrara Formation. The organic carbon-rich interval within the Niobrara Formation has been identified as Oceanic Anoxic Event (OAE) 3. Understanding the reason for this distribution of organic carbon within the Niobrara Formation requires a refined understanding of the source and maturity of the organic matter. In this study, we present lipid biomarker records from the USGS Portland #1 core (Cañon City, CO) to constrain the thermal maturity of the organic matter and the differing contributions of organic matter sources. Sterane and hopane thermal maturity indices indicate that the samples are somewhat immature with respect to oil formation and that there is strong agreement between different proxies for thermal maturity. Based on the distribution of n-alkanes, steranes, and hopanes, there is a significant increase in the contribution of algal organic matter during and after OAE 3, coeval with increased organic carbon accumulation. Although a consistent terrestrial contribution is observed, it is only a minor source of organic matter at the Portland core location and does not drive increased organic matter accumulation during OAE 3. Of particular note is the consistent influence of even-over-odd predominantly mid-chain length (C21 to C25) organic matter. This observation within the brackish to marine, not methanogenic WIS represents an expansion of the depositional settings in which even-over-odd predominance has been observed in mid-chain length n-alkanes. Pristane (Pr) and phytane (Ph) abundances are inconsistent with a redox control on Pr/Ph ratios and suggest an increase in the delivery and/or preservation of phototrophic organic matter as the source for pristane and phytane in the Portland core. 相似文献
19.
《Marine and Petroleum Geology》2012,36(1):55-74
Hydrocarbon source rocks (i.e. Tard Clay Formation), containing type-II organic matter, were deposited in the Hungarian Paleogene Basin during Lower Oligocene. A major contribution of aquatic organisms (green algae, dinoflagellates, Chrysophyte algae) and minor inputs from macrophytes and land plants to organic matter accumulation is indicated by n-alkane distribution patterns, composition of steroids, and δ13C of hydrocarbon biomarkers. Microbial communities included heterotrophic bacteria, cyanobacteria, chemoautotrophic bacteria, as well as green sulphur bacteria. The presence of methanotrophic bacteria is indicated by 13C-depleted hop-17(21)-ene. Higher inputs of terrestrial organic matter occurred during deposition of the lower and uppermost units of the Tard Clay Formation. The terpenoid hydrocarbon composition argues for angiosperm-dominated vegetation in the area of the Hungarian Paleogene Basin. Diterpenoid hydrocarbons, derived from the resins of conifers, are about 2–3‰ enriched in 13C compared to the angiosperm biomarkers.Environmental conditions changed from marine to brackish, accompanied by oxygen-depletion in the lower parts of the water column. Organic carbon accumulation during this period was a consequence of stagnant bottom water conditions in the Hungarian Paleogene Basin due to salinity stratification. This is indicated by low pristane/phytane ratios (varying from 0.27 to 1.44), enhanced ratios of dimethylated versus trimethylated MTTCs (0.14–0.59), and the presence of aryl isoprenoids (from 0.4 to 14.1 μg/g TOC). A major marine incursion is evidenced by stable isotope ratios of organic matter and carbonates. In the uppermost member of the Tard Clay, a transition from brackish towards normal marine conditions is proposed.Up to 3 anoxic cycles are recognized in the drill core sections, separated by minima in pristane/phytane ratios and maxima in the depth trends of di-/tri-methylated MTTCs and aryl isoprenoid concentrations. In combination with the position of maxima of δ13C of carbonate and organic matter and an abrupt decrease in perylene concentrations, the cycles can be used for intra-formational correlation of the Tard Clay. 相似文献
20.
根据X井钻遇的古近系和新近系有机质镜质体反射率分析,确定X井生烃门限深度在2 600m以下,那么该井钻遇始新统流沙港组泥岩有机质丰度较高的井段（2 100~2 285m）尚未达成熟门槛,而生烃门限以下的烃源岩有机质丰度较低,生烃潜力差,不能提供充足的烃源供给,故导致X井勘探失利。X井位于北部湾盆地迈陈凹陷东3洼南部边缘,钻遇流沙港组厚度达568.5m,且泥岩厚度占该组地层的62.3%,其中单层泥岩最大厚度高达115m,表明流沙港组沉积时期水体环境偏深,沉积可容空间大,可见X井钻探结果与前人＂迈5号同生断裂始新世活动弱,沉积可容空间小,导致东3洼缺少油气形成的物质基础＂的结论存在较大偏差。由于X井处在东3洼陷边缘,流沙港组顶部剥蚀强度较大,推测靠近东3洼沉降中心的始新统流沙港组湖相泥岩沉积厚,埋深亦加大,完全能够达到有机质成熟生烃门槛,故应具有较好的油气成藏地质条件和勘探潜力。 相似文献